Youtube Doppleganger

For three weeks now I have been rating youtube videos under to different accounts.  One account prefers to watch music videos and movie trailers while the other account prefers to watch stand up comedy and magic tricks. 

For both accounts ratings were done by adding the videos to the "Favorites" list and by using a 1 to 5 star system.  

Searching for 'comedy' and 'card tricks' in each account yields mostly the same results with roughly 10% difference.  'Comedy' yields the same results for both.  

The main page, channels, and 'video' section for each always shows the same items.  

The interesting thing is that the 'Promoted Videos' are different for each always.